EP0097774A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Transducing system
Assignee: International Business Machines Corp
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Filing: 1983-04-05
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Granted: —
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Expires: 2003-04-05
Abstract
Abstract The surface of a magnetic recording disk (M) is encoded with optically sensed indicia (OT), which is employed to control track following of a read/write slider (17) carrying a magnetic head (19) along a magnetic recording track (MT). The optical reader is a laser (21) carried by the slider which co-operates with the disk as a reflector which completes the lasing function or modulates the operating characteristic of the laser. The retro-reflected light changes the operating voltage of the laser diode. The disk is coated with a multiple layer optical recording medium deposited upon the upper surface of a magnetic recording layer.
Inventors
- 👤 Kie Yeung Ahn
- 👤 Thomas Herman Distefano
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 13:50
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59677; G11B5/74; G11B5/82
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
96 words
1 A magnetic transducing system comprising a magnetic recording disk (9) and a magnetic transducing head (19) carried by a slider (17), characterised in that the disk (9) carries a layer (12) of magnetic material, and includes a servo track layer (8) which is encoded with optically readable servo information (OT-9, OT-10, OT-11) in the form of optical reflectivity variations, and in that the slider (17) carries a laser optical transducer (21) which interacts with the disk to detect such optical variations and to modulate the operation of the laser as a function of the reflectivity.
Claim 2
Dependent Claim
96 words
1 A magnetic transducing system comprising a magnetic recording disk (9) and a magnetic transducing head (19) carried by a slider (17), characterised in that the disk (9) carries a layer (12) of magnetic material, and includes a servo track layer (8) which is encoded with optically readable servo information (OT-9, OT-10, OT-11) in the form of optical reflectivity variations, and in that the slider (17) carries a laser optical transducer (21) which interacts with the disk to detect such optical variations and to modulate the operation of the laser as a function of the reflectivity.
Claim 3
Dependent Claim
77 words
2 A system according to claim 1, in which the laser transducer comprises a semiconductor diode injection laser (21) which directs light from a laser source towards the disk, the laser source being adapted to receive retro-reflective light from the disk, without the assistance of refractive optical elements such as lenses, the laser source having an output voltage varying as a function of the quantity of retro-reflected light received from the disk as a function of time.
Claim 4
Dependent Claim
33 words
3 A system according to claim 2, in which the laser source has an electrical output circuit connected to a circuit for detecting the variations in output signal from the laser source (Fig.13).
Claim 5
Dependent Claim
81 words
4 A system according to claim 1, 2 or 3, in which the medium is encoded with an optical servo track with alternating indicia on opposite sides of the track of the magnetic data, whereby the frequency of modulation of the laser by the optical characteristics of the disk is minimal when the laser transducer is on the track of the magnetic data and the frequency is increased substantially when the laser transducer moves off the track of the magnetic data.
Claim 6
Dependent Claim
44 words
5 A system according to claim 4, in which the system includes means for filtering out the electrical response of the laser transducer so that the output rises to the higher frequencies associated with the laser being off the track of the magnetic data.
Claim 7
Dependent Claim
31 words
6 A system according to any preceding claim, in which the servo track layer (8) includes a layer (14) of rhodium coated with a top layer (15) of a dielectric material.
Claim 8
Dependent Claim
20 words
7 A system according to claim 6 in which the layer (14) of rhodium is 25 to 250 nm thick.
Claim 9
Dependent Claim
17 words
8 A system according to claim 6 or 7, in which the dielectric material comprises amorphous silicon.
Claim 10
Dependent Claim
22 words
9 A system according to claim 8, in which the amorphous material is a layer of silicon 10 to 50 nm thick.
Claim 11
Dependent Claim
61 words
10 A system according to claim 6, 7, 8 or 9, in which the laser transducer comprises a GaAlAs diode laser with a wavelength of substantially 820 nm, and the laser output circuit is connected to a filter circuit which will pass signals from the laser when servo track signals generated in the laser are with a predetermined range of frequencies.
Claim 12
Dependent Claim
29 words
11 A system according to any preceding claim, in which an optical sensor (41) is juxtaposed with the laser to sense the modulation of the operation of the laser.
References Cited (Backward Citations)
No citation records indexed.
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